The objective of the proposed research is to understand the metabolic processes governing the breakdown of the extracellular matrix, particularly of collagen, under normal physiological conditions in the uterus, cervix and Graafian follicle. Breakdown must be regulated with extreme precision to maintain full mechanical function during periods of rapid remodeling. Proteolytic enzymes that digest collagen, gelatin, and proteoglycans are of central importance. These matrix metalloproteinases are regulated by mechanisms such as synthesis in response to hormones, activation of zymogen forms by serine proteinases and inhibition by tissue inhibitor of metalloproteinases. The small metalloproteinase of the involuting rat uterus will be characterized with respect to specificity, distribution, and relationship to known genes. The activation of this enzyme and of uterine collagenase by a serine proteinase of the uterus will be explored. This serine enzyme will be purified and characterized. A theory of dilatation of the rat cervix has been advanced, based in a small dermatan-sulfate proteoglycan. This will be tested using hormonal perturbations. Proteases involved in breakdown of the proteoglycan will be studied. Dilatation of the human cervix involves high levels of collagenase in the tissue and in the serum. The use of collagenase and other markers in the diagnosis and understanding of the unfavorable cervix and premature birth will be explored. A perfusion model of ovulation using the immature rat ovary will be applied to the study of the role of collagenase in ovulation. This promises to be a good system for the study of the proteolytic cascade involving plasminogen activators and plasmin in the activation of latent metalloproteinases. The findings will be of interest in understanding the important role of connective tissue matrix breakdown in the normal physiological processes of uterine involution, cervical dilatation and ovulation. The broad principles of matrix breakdown uncovered here would have much wider implications in understanding normal processes such as embryo morphogenesis, skeletal remodeling and regeneration, as well as many disease processes such as cancer invasion and metastasis, arthritis, periodontitis, and epidermolysis bullosa.